Clear polyurethane coatings with excellent virucidal properties: Preparation, characterization and rapid inactivation of human coronaviruses 229E and SARS-CoV-2.

Commercial polyurethane (PU) coating formulations have been modified with 1-(hydroxymethyl)-5,5-dimethylhydantoin (HMD) both in bulk (0.5 and 1% w/w) and onto the coatings surface as an N-halamine precursor, to obtain clear coatings with high virucidal activity. Upon immersion in diluted chlorine bleaching, the hydantoin structure on the grafted PU membranes was transformed into N-halamine groups, with a high surface chlorine concentration (40-43µg/cm2). Fourier transform infrared spectroscopy (FTIR) spectroscopy, thermogravimetric analysis (TGA), energy-dispersive X-ray (EDX), X-ray photoelectron spectroscopy (XPS) and iodometric titration were used to characterize the coatings and quantify the chlorine contents of the PU membranes after chlorination. Biological evaluation of their activity against Staphylococcus aureus (Gram-positive bacteria) and human coronaviruses HCoV-229E and SARS-CoV-2 was performed, and high inactivation of these pathogens was observed after short contact times. The inactivation of HCoV-229E was higher than 98% for all modified samples after just 30 minutes, whereas it was necessary 12 hours of contact time for complete inactivation of SARS-CoV-2. The coatings were fully rechargeable by immersion in diluted chlorine bleach (2% v/v) for at least 5 chlorination-dechlorination cycles. Moreover, the performance of the antivirus efficiency of the coatings is considered as long-lasting, because experiments of reinfection of the coatings with HCoV-229E coronavirus did not show any loss of the virucidal activity after three consecutive infection cycles without reactivation of the N-halamine groups.

Preparation of Highly Stable and Cost-Efficient Antiviral Materials for Reducing Infections and Avoiding the Transmission of Viruses such as SARS-CoV-2.

The current global pandemic due to the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus has demonstrated the necessity to develop novel materials with antimicrobial and antiviral activities to prevent the infection. One significant route for the spread of diseases is by the transmission of the virus through contact with contaminated surfaces. Antiviral surface treatments can help to reduce or even avoid these hazards. In particular, the development of active-virucidal fabrics or paints represents a very important challenge with multiple applications in hospitals, public transports, or schools. Modern, cutting-edge methods for creating antiviral surface coatings use either materials with a metal base or sophisticated synthetic polymers. Even if these methods are effective, they will still face significant obstacles in terms of large-scale applicability. Here, we describe the preparation of fabrics and paints treated with a scaled-up novel nanostructured biohybrid material composed of very small crystalline phosphate copper(II) nanoparticles, synthesized based on a technology that employs the use of a small amount of biological agent for its formation at room temperature in aqueous media. We demonstrate the efficient inactivation of the human coronavirus 229E (HCoV-229E), the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus, and non-enveloped human rhinovirus 14 (HRV-14) (>99.9%) using an inexpensive, ecologically friendly coating agent. The reactive oxygen species produced during the oxidation of water or the more intensive reaction with hydrogen peroxide are believed to be the cause of the antiviral mechanism of the nanostructured material. In contrast to the release of a specific antiviral drug, this process does not consume the surface coating and does not need regeneration. A 12-month aging research that revealed no decline in antiviral activity is proof that the coating is durable in ambient circumstances. Also, the coated fabric can be reused after different washing cycles, even at moderate to high temperatures.

Fast Air-to-Liquid Sampler Detects Surges in SARS-CoV-2 Aerosol Levels in Hospital Rooms.

The COVID-19 pandemic highlighted the dangers of airborne pathogen transmission. SARS-CoV-2 is known to be transmitted through aerosols; however, little is known about the dynamics of these aerosols in real environments, the conditions, and the minimum viral load required for infection. Efficiently measuring and capturing pathogens present in the air would help to understand the infection process. Air samplers usually take several hours to obtain an air sample. In this work a fast (1-2 min) method for capturing bioaerosols into a liquid medium has been tested in hospital rooms with COVID-19 patients. This fast sampling allows detecting transient levels of aerosols in the air. SARS-CoV-2 RNA is detected in aerosols from several hospital rooms at different levels. Interestingly, there are sudden boosts of the SARS-CoV-2 load in the air, suggesting that SARS-CoV-2 could be released abundantly at certain moments. These results show that the distribution of SARS-CoV-2-containing aerosols is not homogeneous in the hospital room. This technology is a fast and effective tool for capturing airborne matter in a very short time, which allows for fast decision-making any kind of hazard in the air is detected. It is also useful for a better understanding of aerosols dynamics.

Assessment of Surface Disinfection Effectiveness of Decontamination System COUNTERFOG® SDR-F05A+ Against Bacteriophage ɸ29.

The experience of COVID19 pandemic has demonstrated the real concern of biological agents dispersed in the air and surfaces environments. Therefore, the need of a fast and large-scale disinfection method has arisen for prevention of contagion. COUNTERFOG® is an innovative technology developed for large-scale decontamination of air and surfaces. The objective of this study is to assess experimentally the effectiveness of COUNTERFOG® in disinfecting viral-contaminated surfaces. We also aim to measure the necessary time to disinfect said surfaces. Stainless steel surfaces were contaminated with bacteriophage φ29 and disinfected using COUNTERFOG® SDR-F05A+, which uses a sodium hypochlorite solution at different concentrations and for different exposure times. A log reduction over 6 logs of virus titer is obtained in 1 min with 1.2% sodium hypochlorite when the application is direct; while at a radial distance of 5 cm from the point of application the disinfection reaches a reduction of 5.5 logs in 8 min. In the same way, a higher dilution of the sodium hypochlorite concentration (0.7% NaOCl) requires more exposure time (16 min) to obtain the same log reduction (> 6 logs). COUNTERFOG® creates, in a short time and at a distance of 2 m from the point of application, a thin layer of disinfectant that covers the surfaces. The selection of the concentration and exposure time is critical for the efficacy of disinfection. These tests demonstrate that a concentration between 0.7- 1.2% sodium hypochlorite is enough for a fast and efficient ɸ29 phage inactivation. The fact that ɸ29 phage is more resistant to disinfection than SARS-CoV-2 sustains this disinfection procedure.